Pressure control devices are frequently employed to regulate and channel flows of fluids, i.e. liquids or gases. Such pressure control devices often utilize electro-mechanical transducers, such as solenoids, to actuate hydraulic or pneumatic valves in order to regulate fluid flow.
Typically, fluid regulation via a solenoid is accomplished with an open-loop type of control, i.e. control input to the system is computed based on the system's current state and an existing system model. Hence, any system having its fluid flow regulated in such fashion generally lacks feed-back to determine whether the control solenoid input has achieved a desired outcome.
In automotive applications, pressure control devices employing solenoids are often utilized in automatic transmissions to regulate flow of oil into and throughout the subject transmission. In automatic transmissions, such pressure control devices are usually installed in transmission valve bodies, or in transmission control units or modules, and are employed to gain precise control of transmission shift patterns and gear ratios.